He was jailed for three months but a Thai court judge later halved the sentence and ruled Savage could be freed immediately.

Today a Foreign and Commonwealth Office spokesman confirmed he had returned to the UK.

Savage, who had lived in Thailand for nine years, was captured on video urging protesters to set fire to the Central World shopping centre in central Bangkok, days before it was torched and destroyed during the Red Shirt protests.

He was filmed wearing a bandana and saying of Central World: "We're gonna loot everything - gold, watches, everything - and then we're gonna burn it to the ground."

The video was widely distributed on the internet.

Savage, who worked intermittently as a general porter in the kitchens at Buckingham Palace during a five-year period from 1993, denied any involvement in the destruction of the shopping centre and said he was being "stitched up" when he was arrested and taken to a Bangkok remand prison.

"It's a miracle. I am surprised. There is justice in Thailand. I want justice for all, the dead, Red Shirts and even Yellow Shirts," he said, referring to a rival protest group.

Judge Sawaisuwanwong said the sentence was halved because Savage is not a Thai national and had no political stake in the protests.

The judge ruled Savage, who is reported to have been living with his elderly parents in the beach resort of Pattaya, could be released immediately having already served time in custody since his arrest in May.